Why weight matters with the size of the board you get, and not height?
Why a free-style board is a shorter board with more flex? how a shorter board gives more control and maneuverability.
Why a free-ride is a longer board, stiffer, and more stable?

I'm having a bit of trouble understanding how some people say a softer free-style board lets you turn more easily, and then reading that a longer free-ride board is more stable and allows quicker edge to edge transition.

Why weight matters with the size of the board you get, and not height?

neither of them matter that much, the type of riding you do dictates board size more than anything

Why a free-style board is a shorter board with more flex? how a shorter board gives more control and maneuverability.

they are shorter so they are easier to throw around and manipulate, a board that is torsionally softer is easier to turn at slower speeds, therefore you can control and manouver it better

Why a free-ride is a longer board, stiffer, and more stable?

because thats what you need for that type of riding, sort of self explanantory

I'm having a bit of trouble understanding how some people say a softer free-style board lets you turn more easily, and then reading that a longer free-ride board is more stable and allows quicker edge to edge transition.

how quick a board is edge to edge has to do with its sidecut and waist width, not how long it is

Why weight matters with the size of the board you get, and not height?

They both matter. Height just matters very little unless you're oddly built. Weight determines how much you flatten the board out when you ride it. If you are too heavy, the board will have no pop. If you are too light, you won't be able to ride the board the way it was intended. If you are 6'3 and 120 pounds, you may not want to go with a small board. Height matters here because your stance may be wider than the board allows. My suggestion: Eat a friggin Kit Kat.

Why a free-style board is a shorter board with more flex? how a shorter board gives more control and maneuverability.

Boards have more flex so they can do tricks better. You want a board that will be soft and easy to work with in terrain parks or while doing jumps. A stiff board is very unforgiving. They are smaller because a smaller board is easier to throw around. The bigger the board, the harder it is to maneuver. You can use a big board in the park, but it requires more effort.

Why a free-ride is a longer board, stiffer, and more stable?

Big boards tend to float on powder more easily. A small board will sink in a bit, but a big one stays on top. They are stiffer because carving on a soft board is not easy and can lead to a lot of weird chatter at higher speeds. You want stability on powder more than forgiveness.

I'm having a bit of trouble understanding how some people say a softer free-style board lets you turn more easily, and then reading that a longer free-ride board is more stable and allows quicker edge to edge transition.

Not really sure what you mean here. Soft boards aren't any easier or harder to turn in my experience. And I don't think length has anything to do with transitions...